Permanent magnet (PM) machines are favored for fuel cell and hybrid electric vehicle operations due to their desirable characteristics—i.e., good torque density, good overall efficiency, good constant power range, etc. The rotor field in a permanent magnet machine is obtained by virtue of its structure, unlike other machines such as induction, switched or synchronous reluctance machines, in which the field is generated by a stator current supplied by a source. As a result, permanent magnet machines exhibit superior efficiency as compared to other such machines.
However, cooling of such PM machines is a significant challenge, particularly with respect to heat generated at the end turns of the windings (at opposite ends of the stator stack) and within the stator body itself. Current fluid-cooled methods incorporate the flow of some form of cooling fluid, such as water ethylene glycol (WEG), in a cooling assembly and housing that is large, inefficient, and requires complicated fixturing to interface with the stator itself.
Accordingly, it is desirable to provide improved, compact cooling systems for PM machines. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.